Seamless cavity performance

Laboratories in the US begin to take a serious look at hydroforming as a method for creating ILC-type cavities.

Researchers in the US may soon be pumping their cavities into shape.

Last year Fermilab scientists put out a call to industrial companies to propose a procedure for hydroforming ILC-type cavities. They hope that by next year, the selected company will provide Fermilab with three hydroformed nine-cell cavities for testing.

“Hydroforming’s a good idea whose time has come,” said Fermilab scientist Andy Hocker, who has led the lab’s effort in hydroforming research.

To hydroform ILC cavities, a seamless tube of niobium with the right mechanical properties is set in a cavity-shaped die. Water, pressurised to hundreds of atmospheres, is pumped into the tube and pushes out against the tube wall until it conforms to the mould. In ten minutes, the metal is shaped into the cavity’s familiar beads-on-a-string form.

The resulting shape, sculpted from a single piece of metal, is without seams or welds. Scientists see this as the method’s primary advantage over the standard procedure for forming cavities. There, 18 cup-shaped half-cells are each welded by an electron beam to the next, forming the nine-cell structure.

“The weld is such a trouble spot,” Hocker said. Welding is a complicated process, each step of which invites error. Also, most of the consequential defects in the cavity appear near welds (especially those at the equator, the widest part of the cell). “They’re a headache. Everybody would love to be rid of them.”

Being rid of them could also mean potential cost savings in fabrication and improved reproducibility in performance.

The process of hydroforming cavities from niobium tubing has been extensively researched at DESY. Waldemar Singer has led this effort within the Coordinated Accelerator Research in Europe programme. Kenji Saito has led similar R&D at KEK in Japan. Both laboratories have successfully fabricated multi-cell cavities with their developed-in-house hydroforming machines. The DESY effort, in particular, is at a stage where industrialisation is the next logical step.

Osprey pair makes Fermilab home again

Accelerator Division's Greg Vogel submitted this photo of an Osprey pair, which have returned to nest for a third year near the Main Injector.

In the News

Details of final FY 2011 appropriations bill emerging

From FYI: The AIP Bulletin of Science Policy News, April 12, 2011

Following last Fridays night’s final negotiations on a bill to fund the federal government through September 30 of this year, the staff of the House and Senate Appropriations Committees worked to specify the cuts that would be made to department and agency programs. Racing to complete the 459 page bill in order for it to be considered on the House and Senate floors this week, the legislation was filed in the House this morning at 2 a.m.

Current short-term funding expires on April 15, more than six months into FY 2011. Under the deal stuck last week, a total of $38.5 billion was cut from current spending levels (which includes the previous reductions that were made in other short-term funding measures.) A House Appropriations Committee release explained “when this agreement is signed into law, Congress will have taken the unprecedented step of passing the largest non-defense spending cut in the history of the history of our nation – tens of billions larger than any other non-defense reduction, and the biggest overall reduction since World War II.” Total FY 2011 funding will be $78.5 billion less than that requested by the Obama administration.

R2-D0 saves the day

Mike Matulik, group leader of the Infrastructure Group in PPD’s Electrical Engineering Department, wrote this week’s column.

Mike Cherry (left) and Mike Matulik with the robotic system, R2-DO.

Colliding beam detectors like CDF and DZero are most cost efficient when they’re running and taking data 24 hours a day. Yet these complex devices are prone to occasional component failures. Minimizing these interruptions is a major responsibility of support groups such as the DZero Electrical Support Group in the Particle Physics Division. We closely work with the scientists performing the experiments to optimize the detectors’ performance.

Now we have an extra helper in our group, named R2-D0. This robot, conceived by Mike Cherry, can switch power supplies for DZero’s Silicon Micro Tracker detectors without the Main Control Room shutting down the Tevatron. Other accelerator-based experiments may soon ask for similar robots.

The SMT detectors, installed in the center of the DZero detector, help locate the spot where a proton and antiproton collide. Six crates of electronics, located in the collision hall, collect the data generated by the SMT system, and each crate has its own power supply. These power supplies are heavily taxed. When one of them fails, it can take 10 or more hours to finish the data taking with the Tevatron collider before technicians have the opportunity to enter the collision hall to make the replacement. During this time, the DZero experiment can only record a reduced data set, affecting the quality of the DZero data.

When our group discussed how to reduce the impact of these power supply failures, Cherry suggested—perhaps in jest—that we should install a robot to change the power supplies remotely. When we found no other options that were practical to implement, Cherry proceeded to put together a prototype, held together with C-clamps and operated with a hand drill. He convinced us that the robot could work. We thought “R2-D0” was a natural fit, and we adopted the name without a lengthy Star Wars discussion.

Cherry’s design was refined, and we proceeded to connect all six SMT crates to R2-D0 power transfer switches. Earlier this month, we registered our first R2-D0 save: the power connections from a failed power supply were remotely transferred to a second supply while the Tevatron kept running.

Our group gratefully acknowledges the significant
contributions of the DZero Operations Group in PPD to the realization of R2-D0. To
paraphrase an old saying: it takes a division to support a great experimental
program.

Safety Update

ES&H weekly report, April 12

This week's safety report, compiled by the Fermilab ES&H section, includes two incidents. An employee bumped his or her head on a piece of unistrut and another was hit in the foot by a crowbar that fell out of a vehicle.